% This program is used for critical frequency calculation at fixed loaction
% and time. Input parameters are latitude (input value range: -60-60), 
% longitude (input value range: -180:180), local hour (input value range: 1-24 int)
% and day of year (input value range: 1-365 int). This function output the
% sporadic E layer critical frequency. The empiral model is developed by
% Niu Jun and Fang Han-xian of College of meteorology and oceanography, 
% National University of defense technology and all copyrights of this model
% are reserved. For further assistance on this model, please contact us!
% Email address: 990653674@qq.com
function foEs=foEs_calculation(lat,lon,lt,doy)
load model_output.mat
index1=ceil(lat/5)+13;
index2=ceil(lon/5)+37;
foEs=model_output(index1,index2,lt,doy);
end